1. Field of the Invention
This invention relates to a dumping apparatus for a bag filled with molten substance which pulls out, from within a carrying can which has been transported to the dumping apparatus together with a bag accommodated therein and filled with molten substance, the bag and transfers it to a pallet.
2. Description of the Prior Art
A dumping apparatus is already known and disclosed, for example, in U.S. Pat. No. 4,724,656 wherein a tippler to which a paper bag filled with asphalt latex or asphalt in a molten condition (such paper bag will be hereinafter referred to as bag filled with asphalt latex) is transported by means of a roller conveyor while accommodated in a carrying can is moved to take up the carrying can from the roller conveyor and then incline the carrying can downwardly while held thereon so that the bag filled with asphalt latex is pulled out from within the carrying can and transferred to a pallet.
The tippler of the dumping apparatus includes a pair of disks each having a window hole formed therein through which a carrying can pass and a plurality of rods which can hold a carrying can thereon. Each of the disks has serrations or teeth formed on an outer periphery thereof. The tippler is mounted for rotation on a travelling frame, which is moved horizontally together with the tippler. The serrations of the disks are held in direct engagement with a pair of racks, and the travelling frame is connected to a motor by way of a chain so that it may be moved back and forth by the motor. Or else, small gears are provided between the serrations of the disks and the racks such that they mesh with both of the latter. The racks are connected to piston rods of a pair of cylinders so that the travelling frame may be moved back and forth by contracting and expanding movements of the piston rods. When the travelling frame is moved back and forth, the tippler is moved back and forth away from and toward a pallet together with the travelling frame.
Meanwhile, a pallet conveyor for transporting a pallet from a transfer position of a bag filled with asphalt latex is mounted on a conveyor frame which is supported on a conveyor truck for upward and downward tilting motion around an end portion thereof remote from the tippler. The conveyor frame is pivoted from a normal horizontal position to an upwardly inclined position and then pivoted back to the normal horizontal position when a piston rod of a cylinder which is provided between the conveyor frame and the conveyor truck is expanded and then contracted. Further, the conveyor truck is separably connected to a slide rod to which rotation of a motor is transmitted after it is converted into linear motion so that the conveyor truck may be moved toward and away from the tippler by rotation of the motor.
With the conventional dumping apparatus, a carrying can held on the tippler is inclined downwardly while being moved horizontally toward a pallet by the tippler, and simultaneously the pallet is moved toward the tippler while it is being inclined such that an end portion thereof adjacent the tippler may be raised. Consequently, a bag filled with asphalt latex is discharged from the carrying can, whereupon an end portion thereof is received on the pallet which is inclined in the same direction as the bag filled with asphalt latex. After then, the carrying can is returned to its upwardly directed position while it is being retracted away from the pallet, and simultaneously the pallet is returned to its horizontal position. As a result of such returning movement, the bag filled with asphalt latex in the carrying can is let off from the carrying can and thus transferred to the pallet.
The dumping apparatus, however, has such problems as described below.
In particular, first, since the tippler is bodily moved forwardly or backwardly while being rotated, the driving mechanism therefor is complicated in structure and consequently is expensive, and besides since a large number of driving parts are involved, a high power is required.
Further, since the tippler is moved back and forth together with the travelling frame, the dumping apparatus is large in overall size.
Besides, since the tippler is moved horizontally toward a pallet while it is being rotated, a carrying can is tilted down while being advanced drawing an elliptic locus and the bag filled with asphalt latex in the carrying can is almost thrown to the pallet. Accordingly, the impact when an end portion of the bag filled with asphalt latex drops on the pallet is high.
In addition, since the carrying can rises, upon returning movement of the tippler, while being retracted drawing an elliptic locus, it will raise a portion of the bag filled with asphalt latex which has not been drawn out fully from and still remains in the carrying can. In this instance, since the asphalt in the paper bag still remains in a molten condition of a high temperature (for example, 200.degree. C. or so), the bag filled with asphalt latex is flexible with a high weight. Therefore, when the portion of the bag filled with asphalt latex which remains in the carrying can is lifted by the rising carrying can, an edge of the mouth of the carrying can acts as if it bites into the bag filled with asphalt latex. Then, in this condition, the bag filled with asphalt latex is lifted while the mouth edge of the carrying can rubs the paper bag which is now in a weakened condition due to heat of the asphalt latex, and on the other hand, the bag filled with asphalt latex is drawn out fully from the carrying can while being lifted in this manner and then drops onto the pallet. Therefore, the probability that the paper bag may be broken is high. If the paper bag is broken, then the asphalt latex in a molten condition of a high temperature will leak from the paper bag and may soil not only the pallet but also the pallet conveyor, the conveyor frame, the conveyor truck and the driving apparatus for them, and much time and labor will be required for cleaning of them.